QuoteAdjusting hammer preload in a regulated gun, really is not the right way for power increases/decreases, unless you are only looking at minor fps tweaks. It is mainly needed to follow the reg pressure adjustment. If you raise the pressure, it takes more energy to break the poppet free from the seat. Hence needing preload on the spring. Drop the reg pressure, and need to lower hammer energy, or will start over-dwelling and wasting air. Does this not contradict what Steven has done in his video? His results are pretty impressive.
Adjusting hammer preload in a regulated gun, really is not the right way for power increases/decreases, unless you are only looking at minor fps tweaks. It is mainly needed to follow the reg pressure adjustment. If you raise the pressure, it takes more energy to break the poppet free from the seat. Hence needing preload on the spring. Drop the reg pressure, and need to lower hammer energy, or will start over-dwelling and wasting air.
Quote from: USAFANG6799 on February 13, 2019, 09:48:45 AMQuoteAdjusting hammer preload in a regulated gun, really is not the right way for power increases/decreases, unless you are only looking at minor fps tweaks. It is mainly needed to follow the reg pressure adjustment. If you raise the pressure, it takes more energy to break the poppet free from the seat. Hence needing preload on the spring. Drop the reg pressure, and need to lower hammer energy, or will start over-dwelling and wasting air. Does this not contradict what Steven has done in his video? His results are pretty impressive.No, I don't think it does. I believe he is running with the reg set significantly higher than stock. From one of his other videos, I think in the 2600-2700psi range. Generally, you want to be running just below the knee in the curve. At the knee, you apply more preload and get less increase out of it. Assuming he still running in that range, he could start dropping the reg pressure, then run the preload up to just below the knee. The lower he can get the reg pressure and still reach the power he wants at just below the knee, the better the shot count.
Quote from: stretch on February 13, 2019, 08:55:36 AMI pumped my Liberty to (what I thought was) 4,100 psi on Monday and then when I looked at it Tuesday morning it looked like the pressure had dropped to 3,800 psi. I may not have looked at the gauge very carefully on Monday, so I took a photo Tuesday morning and then again this morning (24 hours later). If you look carefully, it does look like the needle has dropped maybe 80 psi. The rifle has sat on my bench in the house, so there haven't been any major temperature changes. Is this a big enough leak to be concerned about? What do the PCP experts think?Hey stretch, Did you try to tighten a bit the bleeding screw at the bottom of the stock?
I pumped my Liberty to (what I thought was) 4,100 psi on Monday and then when I looked at it Tuesday morning it looked like the pressure had dropped to 3,800 psi. I may not have looked at the gauge very carefully on Monday, so I took a photo Tuesday morning and then again this morning (24 hours later). If you look carefully, it does look like the needle has dropped maybe 80 psi. The rifle has sat on my bench in the house, so there haven't been any major temperature changes. Is this a big enough leak to be concerned about? What do the PCP experts think?
but this is also interesting: when only playing with 2 variables, HST and regulator set point what you described is right, but check this thread, add another variable (the transfer port opening) and now higher pressures can lead to more efficiency.... https://www.gatewaytoairguns.org/GTA/index.php?topic=154625.msg155704114#msg155704114
Quote from: Orion on February 13, 2019, 12:00:34 PMbut this is also interesting: when only playing with 2 variables, HST and regulator set point what you described is right, but check this thread, add another variable (the transfer port opening) and now higher pressures can lead to more efficiency.... https://www.gatewaytoairguns.org/GTA/index.php?topic=154625.msg155704114#msg155704114The pressure where the gun is most efficient, might not result in highest shot count, ie what Allan said in that thread. So lets say that the gun is more efficient at 2600 then 2000. At 2600 you are working with 4K to 2.6K, but for the latter 4k to 2k. Yes, porting is another variable, as is the plenum size. The small plenum, I feel, is holding this gun back, more than anything.
Quote from: Abefroman on February 13, 2019, 09:04:07 AMHey Guys - I've done a few mods to my liberty, but my shot groups are all over the place and I cant figure out why. I've turned the regulator 1/2 turn ccw and shimmed the hammer spring with two washers, ported the barrel and power knob to 3/16" and I'm getting around 900+ish with H&N Baracuda Match 21.14 and 920+ish with JSB 18.1 grain. I've adjusted the regulator and the hammer spring shims many many times, but at 50 yards, my groups are still all over the place. My .22 gauntlet is extremely accurate at 50 yards. So, I'm kinda perplexed here. I think my next task is to take the barrel off and clean the H*LL out of it. And then maybe crown the barrel. I'm also gonna swap out the scope in case that is the problem, but I doubt it is. Other than that, I dont know what to do. Last night I shot a string of the baracuda match 21.14 grains and i actually got 3 shots in a row pretty much in the same spot, but then my follow up shots were 8 inches away !!! what's going on here ? anyone? CheersYou are running at a power level and using pellets that others have reported decent accuracy, so would not try to adjust reg/spring to fix this. Starting with a good cleaning of the barrel, checking the crown and leade for burrs, and for any damage in the rifling. For accuracy testing, use the ss tray and make sure pellet centered in channel and close bolt slowly, to feed evenly into leade. Also check the shroud end cap for possible clipping. Even try it without the endcap or any baffles, if you installed them. It is going to be loud, but if the flyers go away, that is a good clue.
Hey Guys - I've done a few mods to my liberty, but my shot groups are all over the place and I cant figure out why. I've turned the regulator 1/2 turn ccw and shimmed the hammer spring with two washers, ported the barrel and power knob to 3/16" and I'm getting around 900+ish with H&N Baracuda Match 21.14 and 920+ish with JSB 18.1 grain. I've adjusted the regulator and the hammer spring shims many many times, but at 50 yards, my groups are still all over the place. My .22 gauntlet is extremely accurate at 50 yards. So, I'm kinda perplexed here. I think my next task is to take the barrel off and clean the H*LL out of it. And then maybe crown the barrel. I'm also gonna swap out the scope in case that is the problem, but I doubt it is. Other than that, I dont know what to do. Last night I shot a string of the baracuda match 21.14 grains and i actually got 3 shots in a row pretty much in the same spot, but then my follow up shots were 8 inches away !!! what's going on here ? anyone? Cheers
What's the "optimum" fill pressure people are finding for their stock / unmodded .22? I seem to remember someone posted that they only fill to 3,600 psi because that was the start of their optimum pressure?
Quote from: stretch on February 13, 2019, 05:50:59 PMWhat's the "optimum" fill pressure people are finding for their stock / unmodded .22? I seem to remember someone posted that they only fill to 3,600 psi because that was the start of their optimum pressure?stretch, I think I'm having the same drop in pressure that you just described, I'll keep an eye on it
It took my regulator time to settle in, still get an occasional hiccup but most shots are pretty consistent
Quote from: FuzzyGrub on February 13, 2019, 11:47:29 AMQuote from: USAFANG6799 on February 13, 2019, 09:48:45 AMQuoteAdjusting hammer preload in a regulated gun, really is not the right way for power increases/decreases, unless you are only looking at minor fps tweaks. It is mainly needed to follow the reg pressure adjustment. If you raise the pressure, it takes more energy to break the poppet free from the seat. Hence needing preload on the spring. Drop the reg pressure, and need to lower hammer energy, or will start over-dwelling and wasting air. Does this not contradict what Steven has done in his video? His results are pretty impressive.No, I don't think it does. I believe he is running with the reg set significantly higher than stock. From one of his other videos, I think in the 2600-2700psi range. Generally, you want to be running just below the knee in the curve. At the knee, you apply more preload and get less increase out of it. Assuming he still running in that range, he could start dropping the reg pressure, then run the preload up to just below the knee. The lower he can get the reg pressure and still reach the power he wants at just below the knee, the better the shot count.My goal is to be able to shoot jsb monsters at 920fps as efficiently as possible. Set regulator and HST with TP at 3/16" for the heavies pellets. Then lower hammer spring tension to shoot lighter pellets. The way I see it, If I can get, let's say, 30 shots of jsb monsters 25 grain at 920fps then I should be able to get 40 shots with H&N 21 grain at 900 for and then 50 shots with jsb heavies 18 grain at 890fps. Please correct me if I've got this wrong.
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